Stuffer plug for automotive extrudate

ABSTRACT

A process and apparatus for insertion of a stuffer plug ( 18 ) within a hollow section of a automotive weatherseal extrudate ( 10 ) is provided which operates by insertion of a needlelike section ( 20 ) of a dispenser unit through a wall of the extrudate into the hollow section. A stuffer plug precursor is then injected or inserted into the hollow section and the needle-like section of the dispenser is removed. The stuffer plug precursor ( 22 ) then forms a stuffer plug ( 18 ) within the hollow section. Preferably, the stuffer plug is a two part polyurethane which reacts chemically to form a polyurethane foam stuffer plug ( 18 ) within the hollow section. An easier method for establishing a stuffer plug ( 18 ) within an extrudate ( 10 ) is provided.

CROSS-REFERENCE TO RELATED APPLICATIONS

This applications claims priority of U.S. Provisional Patent ApplicationSer. No. 60/473,488 filed on May 28, 2003, entitled “Stuffer Injectionfor Automotive Extrudate”.

FIELD OF THE INVENTION

The present invention relates to the field of stuffing of automotiveextrudate, and in particular, relates to a device and process forinserting a stuffer plug within an extrudate.

BACKGROUND OF THE INVENTION

Extrudates are commonly used to produce materials used in automotiveapplications, such as, for example, in weatherseals or the like. Suchweatherseals are primarily used to provide seals against wind, rain,noise and the like, in situations wherein glass and metal (or othermaterials) are in contact with each other (in fixed or movablesituations), or in situations where metal components (or othermaterials) are in a movable relationship to one another, such as, forexample, a door, trunk or hood opening with respect to the frame or bodyof the automobile.

The term “extrudate” is used since these materials are typicallymanufactured by extruding a selected, extrudable material through anextruder to form a continuous length of the selected material. Theextruded material may then be, if necessary, cut to length, and/or bentor shaped to form the desired “extrudate” material.

By “extrudable” is meant that a material blend can be processed in anavailable, commercial extruder or injection moulding machine whichprovides internal mixing at a temperature in the range from, forexample, about 180° C. to 240° C. with a residence time less than 5 min,preferably in the range from 30 sec to 2 min.

Extrudates in the automotive industry, and in particular weatherseals,are typically produced as a long, hollow ribbon of flexible material.The flexible material is chosen to enable the material to be fitted tothe body of the automobile. The extrudate is commonly hollow to allowfor increased flexibility, and reduce weight and costs by minimizing theamount of material used. As such, there are commonly one or morepassages, or passageways, which are at least partially, and commonly,totally enclosed within the extrudate. While these passageways reducethe amount of material used, decrease weight, and allow for increasedflexibility of the extrudate, it can be desirable under certaincircumstances to strengthen or otherwise stiffen the extrudate material.In prior art applications, this task would commonly be achieved byinserting a pre-formed plug or “stuffer”, typically made of a foamedmaterial, into a passageway at one end of the weatherseal, and usingcompressed air to push or otherwise move the plug or stuffer to adesired location within an extrudate passageway.

Alternatively, the plug or stuffer might be formed in the weatherseal byinsertion of a foaming material from a nozzle inserted into thepassageway through one or more ends of the weatherseal, and allowing thefoaming material to form a plug, in situ. While these operations providethe necessary stiffening of the weatherseal, insertion of the plug inthe correct location can be difficult, and commonly involves the use ofmanual labour. Further, it should be noted that these operations arecommonly conducted off of the production line since they are not easilyautomated. The costs of such “off-line” operations can be high, and assuch, it would therefore be desirable to provide an alternative methodfor the placement of stuffers or plugs within the hollow shell and/orpassageways formed within the shell of the extrudate. It would also beadvantageous to provide an alternative method which could be automatedand which would be suitable for “on-line” processes.

SUMMARY OF THE INVENTION

Accordingly, it is a principal advantage of the present invention toprovide a process for the direct insertion of a plug into a passagewaywithin a hollow automotive extrudate.

It is a further advantage of the present invention to provide anautomated device and process for the direct insertion of such a pluginto the automotive extrudate.

The advantages set out hereinabove, as well as other objects and goalsinherent thereto, are at least partially or fully provided by theprocess of the present invention, as set out herein below.

Accordingly, in one aspect, the present invention provides a process forproducing an extrudate having at least one stuffer plug comprisingproviding an extrudate having at least one hollow section within saidextrudate; piercing said extrudate and inserting an operative end of adispenser within said hollow section; inserting or injecting, throughsaid dispenser, a stuffer precursor within said hollow section; removingsaid dispenser from said hollow section; and allowing said stufferprecursor to form a stuffer plug.

In a further aspect, the present invention also provides extrudateproduced from a process as described hereinabove.

In a still further aspect, the present invention also provides anapparatus for establishing a stuffer plug within a hollow section of anextrudate, which apparatus comprises a dispenser having a needle-likesection and a stuffer plug precursor supply means for supplyingprecursor material to said dispenser, wherein the needle-like section iscapable of being at least partially inserted, through the wall of theextrudate, into a hollow section within the extrudate so that a stufferplug precursor material can be fed through the needle-like section ofsaid dispenser unit into the hollow section.

In a still further aspect, the present invention also provides for theuse of an extrudate comprising a stuffer plug which has been establishedwithin the extrudate using a process as described hereinabove withrespect to the present invention.

In a still further aspect, the present invention also provides anextrudate having a substantially hollow section surrounded by a shell,said extrudate comprises a stuffer plug within the hollow section, saidstuffer plug being disposed about a pierced section of the shell.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of this invention will now be described by way of exampleonly in association with the accompanying drawings in which:

FIG. 1 is a perspective view of an extrudate weatherseal component witha cutaway section showing a stuffer plug within a closed passageway;

FIGS. 2A-2E show a series of schematic cross-sectional views of astuffer plug being created within an extrudate, in accordance with thepresent invention;

FIG. 3 is a front view of a work station for using an apparatus forinjection of a stuffer plug within an extrudate;

FIG. 4 is a side view of Section A-A of the apparatus of FIG. 3;

FIG. 5 is sectional view of the injection unit shown in place in theapparatus of FIG. 3; and

FIG. 6 is a top view of the injection unit shown in FIG. 5.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The novel features which are believed to be characteristic of thepresent invention, as to its structure; organization, use and method ofoperation, together with further objectives and advantages thereof, willbe better understood from the following drawings in which a presentlypreferred embodiment of the invention will now be illustrated by way ofexample only. In the drawings, like reference numerals depict likeelements.

It is expressly understood, however, that the drawings are for thepurpose of illustration and description only and are not intended as adefinition of the limits of the invention.

Referring to FIG. 1, an extrudate weatherseal 10 is shown having arubber shell 14. Extrudate 10 is produced in continuous fashion byextrusion, and then cut to length. In the present application, the term“extrudate” refers to any product produced by extrusion of an extrudablematerial. The term “weatherseal” refers to a product used for sealingbetween surfaces, and in particular, to an extruded thermoplasticmaterial intended for use in any application where metal and/or glassparts. The present application is primarily directed to, and describedwith respect to, the use of such extrudates as weatherseals forautomobiles. However, the skilled artisan will be aware that suchextrudates can be used in a wide variety of automotive applications.Further, while the present application is described with particularreference to the automotive industry, the skilled artisan would be awarethat the present application is equally applicable in othernon-automotive applications.

The extrudate weatherseal 10 is formed with at least one hollow section,which hollow section is typically a passageway extending along thelength of the extrudate, and which is at least partially enclosed withinthe extrudate. Most preferably, the passageway is substantiallycompletely enclosed within the extrudate (with the possible exception ofthe ends of the passageway and/or extrudate). While the extrudatetypically has only one passageway, it can, in some circumstances,comprise a plurality of passageways within a single extrudate.

The extrudate weatherseal 10 is preferably a material which has beenfound to be suitable for use as a weatherseal for automotiveapplications. A wide variety of weatherseal materials have been proposedand used, including rubber, synthetic rubber, rubberized materials,plastics, elastomers and the like. A typical weatherseal might befabricated of, for example, elastomers, which can be defined as amaterial which experiences large reversible deformations underrelatively low stress. Some examples of commercially availableelastomers include natural rubber, ethylene/propylene (EPM) copolymers,ethylene/propyleneldiene (EPDM) copolymers, styrene/butadienecopolymers, chlorinated polyethylene, and silicone rubber.

Thermoplastic elastomers are elastomers having thermoplastic properties.That is, thermoplastic elastomers are optionally molded or otherwiseshaped and reprocessed at temperatures above their melting or softeningpoint. One example of thermoplastic elastomers isstyrene-butadiene-styrene (SBS) block copolymer. SBS block copolymersexhibit a two phase morphology consisting of glassy polystyrene domainsconnected by rubbery butadiene segments. At temperatures between theglass transition temperatures of the butadiene mid-block and the styreneend-blocks the SBS copolymers act like a crosslinked elastomer.

In contrast, thermoset elastomers are elastomers having thermosetproperties. That is, thermoset elastomers irreversibly solidify or “set”when heated, generally due to an irreversible crosslinking reaction. Twoexamples of thermoset elastomers are crosslinked ethylene-propylenemonomer rubber (EPM) and crosslinked ethylene-propylene-diene monomerrubber (EPDM). EPM materials are made by copolymerization of ethyleneand propylene, and are typically cured with peroxides to give rise tocrosslinking, and thereby induce thermoset properties. EPDM materialsare linear interpolymers of ethylene, propylene, and a non-conjugateddiene such as 1,4-hexadiene, dicyclopentadiene, or ethylidenenorbornene. EPDM materials are typically vulcanized with sulfur toinduce thermoset properties, although they alternatively are optionallycured with peroxides.

Additional materials include materials commonly referred to asthermoplastics and more particularly to “thermoplastic vulcanizates”(TPVs), and even more particularly to weatherseals made from extrudableTPVs.

Thermoplastic vulcanizates (TPVs) are polyolefinic matrices, preferablycrystalline, through which thermoset elastomers are generally uniformlydistributed. Examples of thermoplastic vulcanizates include EPM and EPDMthermoset materials distributed in a crystalline polypropylene matrix.One example of a commercially available material is Santoprene™.Thermoplastic rubber which is manufactured by Advanced Elastomer Systemsand is a mixture of crosslinked EPDM particles in a crystallinepolypropylene matrix. These materials have found utility in manyapplications which previously used vulcanized rubber, e.g. hose,gaskets, and the like. In these applications, TPVs are noted for theirability to be processed as thermoplastics while retaining the excellenttensile and compression set properties of vulcanized rubbers.

Commercial TPV materials are typically based on vulcanized rubbers inwhich a phenolic resin or sulfur cure system is used to vulcanize, thatis to crosslink, a diene copolymer rubber by way of dynamicvulcanization, that is crosslinking while mixing (typically vigorously),in a thermoplastic matrix. Sulfur or a phenolic resin is preferred overperoxide free radical cure systems because peroxide degrades apolypropylene or and crosslinks a polyethylene as well as the rubber andthis is in turn limits the extent of rubber crosslinking that can occurbefore the entire mixture degraded or crosslinked and is no longerthermoplastic.

The thermoplastic material of use in the present invention, ispreferably extrudable, and thus forms a thermoplastic extrudate. Thethermoplastic extrudate is preferably a solid material which isessentially free of macroscopic voids, or alternatively, is a dense foammaterial having a density in the range greater than about 80% of that ofthe solid material. It should be noted, however, that the thermoplasticmaterial of interest in the present invention is typicallyre-processable, unlike a thermoset resin.

Other materials for blending or co-extrusion can include, for example,melt-blended olefin-based elastomers including polypropylene,polyethylene. Other components can include plasticizers, viscositymodifiers such as processing oils or esters, fillers, colourants, curingagents, antioxidants and other ingredients. Suitable fillers can includecalcium silicate, clay, kaolin, talc, silica, diatomaceous earth,powdered mica, barium sulfate, aluminum sulfate, calcium sulfate, basicmagnesium carbonate, glass fibers, and carbon fibers, provided thefiller is used in an amount small enough not to adversely affect eitherthe hardness or the coefficients of friction of the thermoplasticcopolymer.

The components of the weatherseal 10 are preferably selected so as toprovide acceptable weatherseal properties with respect to, for example,known weatherseal performance properties such as flexibility,durability, hardness, UV resistance, and the like. The cross-section ofthe body is preferably adapted to be held in or on a particular portionof an opening which is to be sealed against the weather.

Through the use of appropriate materials, a weatherseal can be producedwhich provides good weatherseal properties such as softness, abrasionresistance and low coefficients of friction. Further, by varying theratios of the components, one may provide desired hardness/softness, oiland temperature resistance, oxidation resistance, and extrudability,inter alia. Additionally, by fabricating a hollow extrudate, the weightof the weatherseal is reduced, and typically, its flexibility isincreased.

It should be clear that the process and apparatus of the presentinvention are of most use wherein the hollow section of the weathersealis essentially completely surrounded by the extruded material (with thepossible exception of the extrudate ends), and thus is essentiallyclosed. While there may be applications wherein the process of thepresent invention is used with an open extrudate (i.e. one that is notessentially closed), it will be clear to the skilled artisan that theprimary advantage of the device and process of the present invention isto provide a plug of material within the closed extrudate, and thusclose and/or seal any or all passageways within the extrudate.

During production, a closed passageway 12 is created which is a hollowsection within shell 14, together with a solid rubber section 16 whichis adapted to be fitted over a metal strip and rest against an adjacentmetal strip (not shown). A portion of shell 14 has been cutaway in orderto reveal a foam stuffer plug 18 which is situated within passageway 12,and acts as a barrier within passageway 12 as well as a reinforcementfor shell 14.

The stuffer plug 18 can be located at any point along the length of theextrudate weatherseal 10, as desired The length of the plug 18 will varydepending on, inter alia, the amount of stuffer precursor used, and thesize of the hollow section. The precursor is any material which iscapable of being inserted or injected into the hollow section which canform into a plug. As such, the precursor might be a compressed foammaterial which will expand once inserted into the hollow section.Alternatively, the precursor might be a melted material injected intothe hollow section which would solidify on cooling in order to form thestuffer plug. If needed, the extrudate weatherseal 10 could betemporarily crimped or sealed in order to contain any liquid within thedesired area of the hollow section of the extrudate 10. Most preferably,however, the precursor is a material which will undergo a chemicalreaction once inserted or injected into the hollow section, and thusform a plug material as a result of the chemical reaction.

Once inserted, the precursor expands by de-compression, chemical orphysical foaming, or as a result of any other chemical or physicalproperty, in order to form a stuffer plug 18. The stuffer plug 18 can,if desired, expand to fill the entire cross-sectional area of the hollowsection of the extrudate 10, at or near the point of insertion of thedispenser, or can be left to only partially fill this area

The plug 18 is preferably made from a flexible material which can bendand/or flex as the extrudate bends, flexes, or otherwise moves. Further,while any suitable material might be used, preferably the plug materialdoes not significantly react with, adhere to, or otherwise affect thesurface of the extrudate material. As such, the plug is preferablymanufactured from a polyurethane foam, and most preferably, from a twopart polyurethane material which reacts within the passageway to form afoam plug material. As such, the plug 18 preferably is a foam material,which foam is preferably formed in situ by a chemical reaction of theplug material within the extrudate 10.

In FIGS. 2A-2E , schematic cross-sectional views of the method forproduction of a foam stuffer plug 18 are shown in 5 stages. In FIG. 2A,a needle-like dispenser unit 20 is shown above an extrudate having ahollow shell 14 around a passageway 12. In FIG. 2B, dispenser unit 20has been moved to pierce shell 14 which collapses as a result of thepressure from unit 20. However, the dispenser unit 20 has pierced shell14. In FIG. 2C, a two-part polyurethane material 22 as a stuffer plugprecursor, which was mixed immediately prior to being fed to dispenserunit 20, is being injected into collapsed shell 14. In FIG. 2D,dispenser unit 20 is removed from shell 14, and the complete charge ofpolyurethane material 22 has been injected into shell 14. Material 22sticks to the inner sides of shell 14 and maintains the shell in apartially collapsed shape.

In FIG. 2E, material 22 has reacted and thereby expanded to form a foamstuffer plug 18 from precursor material 22, and the stuffer plug 18separates shell 14 into two separate hollow passageways 12. Any furtherforce on shell 14 in the region of the stuffer plug, will now actagainst both the extrudate shell, and the stuffer plug.

In FIG. 3, a front view of a work station 30 for using an apparatus toinject a stuffer plug into an extrudate, as shown in FIGS. 2A-2E, isprovided. FIG. 4 provides a cross-sectional view of work station 30,along the line A-A in FIG. 3. Work station 30 is supported by a seriesof stands 32 on which rests a conveyor 34. A length of extrudate 10 lieson conveyor 34. Extrudate 10 has been fed to conveyor 34 using conveyor36, and when stuffer plug 18 has been inserted, extrudate 10 will beremoved using conveyor 38. Extrudate 10 is held in position on conveyor34 using a set of alignment rails 40. A measuring tape 42 is provided inorder to locate dispenser unit 62 (best seen in FIG. 5) in the properposition. Guide rails 44 are provided for moving the dispenser unit 62and its related assembly 60. A support bracket 46 is provided forattaching alignment rails 40 and guide rails 44 to support stands 32.

In FIGS. 5 and 6, a sectional view and a top view, respectively, ofdetails of dispenser unit assembly 60 are provided. The dispenser 60 ispreferably a needle-like assembly which can pierce the extrudate wallwithout causing any significant damage to the outer surface of theextrudate. Dispenser unit 62 is attached to injection unit stand 50,which in turn is attached to positioning bracket 52 which bracket slidesalong guide rails 44. A stop pin 54 is provided on the front of bracket52 and is located next to measuring tape 42. Stop pin 54 can be used to“lock” unit 60 in place when the dispenser unit is being used.

At the lower end of dispenser unit 62 is a needle 64 to pierce theextrudate wall and through which the stuffer plug precursor material canbe fed. Dispenser unit 62 is shown in FIG. 5 in its upward position, andis raised above extrudate 10. Extrudate 10 is held in position byalignment rails 44, and rests on conveyor 34.

The dispenser 60 may be a single hollow needle, or might comprise two ormore needle sections in the case of a chemical reaction wherein thechemical components are kept separate from each other until mixing inthe extrudate passageway. Alternatively, the chemical components mightbe pre-mixed shortly prior to insertion or injection into the hollowsection of the extrudate.

The dispenser 60 might be a hand-held device operated by a manualoperator and might merely comprise a needle-like section connected to astuffer plug precursor material supply. Preferably, however, thedispenser 60 is one part of a dispenser assembly which includes anextrudate channel for holding a length of extrudate 10 in positionwithin the apparatus, a needle-like assembly for piercing the extrudatewall, when in an operative position, so as to be capable of inserting orinjecting a stuffer precursor within a hollow section of the extrudate10, and dispenser unit actuators adapted to move the needle-like sectionof the dispenser to and from the operative position to an inoperativeposition wherein the needle-like assembly is withdrawn from theextrudate 10. The dispensing apparatus 60 might also be movable andinclude means for locating the dispenser at a desired location on theextrudate.

As such, the dispenser 60 may be part of a dispenser assembly, whichdispenser assembly comprises alignment rails 40 for positioning andholding an extrudate 10 in an operative position, guide rails 44 onwhich said dispenser is mounted and on which guide rails. The dispenser60 can be moved by actuators for moving the dispenser 60 from aretracted position where it is not in contact with the extrudate 10 to,and from, an extended position wherein the needle-like section pierces awall of the extrudate 10 and at least a part of the needle-like sectionextends into a hollow section within extrudate 10.

Preferably, the guide rails 44 are essentially parallel to the alignmentrails 40 so that the dispenser unit can be moved along the length of theextrudate 10 held within the alignment rails 40.

Also, preferably the dispenser assembly 60 comprises at least oneconveyor 34 for moving a length of extrudate 10 into an operativeposition within the alignment rails 40. The conveyor 34, such as aconveyor belt, can also be used to re-position the extrudate 10 withinthe rails in order that the dispenser unit can establish two or morestuffer plugs 18 within the extrudate 10.

The assembly for controlling the dispensers, the conveyer, dispenseractuators, and the like, can be controlled by various processors so thatthe apparatus is automated. As such, the assembly can automaticallydetermine and move the extrudate 10 to the proper location for insertionor injection of the stuffer plug 18 within the extrudate 10, and be ableto move the dispenser to an appropriate position for insertion into theextrudate 18.

Using a downstroke cylinder 66, dispenser unit 62 is moved downwards andpierces shell 14 of extrudate 10, in a manner described in FIGS. 2A-2E.Stuffer plug precursor material is fed to dispenser unit 62 throughsupply hose 63. Once the stuffer plug precursor material has beeninjected into hollow passageway 12, dispenser unit 62 is again raisedabove extrudate 10 using upstroke cylinder 68. Conveyor 34 can then beused to move extrudate 10 along the work station, or to be removed fromwork station 30.

It will be understood that work station 30 might have one, or aplurality of dispenser units 62 each of which might be activatedsimultaneously, or in sequential order. It will also be understood thatthe devices of the present embodiment can be controlled by a variety ofprocessing units (not shown), and thus, movement of the extrudate andinjection of the stuffer plug material can be automated so as toeliminate or reduce the need for manual, off-line processing.

Thus, it is apparent that there has been provided, in accordance withthe present invention, a process and apparatus for producing extrudatematerials, and in particular weatherseal extrudates, which comprise astuffer plug which has been inserted or injected into the extrudate, andan apparatus for conducting the process, which fully satisfies thegoals, objects, and advantages set forth hereinbefore. Therefore, havingdescribed specific embodiments of the present invention, it will beunderstood that alternatives, modifications and variations thereof maybe suggested to those skilled in the art, and that it is intended thatthe present specification embrace all such alternatives, modificationsand variations as fall within the scope of the appended claims.

1. An on-line process for introducing a stuffer plug into a hollowsection of an extrudate comprising: extruding an extrudate having atleast one hollow section within said extrudate; providing the extrudateto a dispenser assembly comprising an extrudate channel for holding alength of the extrudate in a predetermined position; piercing anextrudate wall of the at least one hollow section and inserting anoperative end of the dispenser assembly within said hollow section whensaid dispenser assembly is in an operative position; dispensing, throughsaid operative end, a stuffer precursor within said hollow section;removing said operative end from said hollow section to an inoperativeposition; and allowing said stuffer precursor to form a stuffer plug. 2.A process as claimed in claim 1 wherein said extrudate is a weatherseal.3. A process as claimed in claim 1 wherein said extrudate is anautomotive weatherseal.
 4. A process as claimed in claim 1 wherein saidhollow section is a passageway which is at least partially enclosedwithin said extrudate.
 5. A process as claimed in claim 4 wherein saidpassageway is a closed passageway within said extrudate.
 6. A process asclaimed in claim 5 wherein said extrudate comprises two or more closedpassageways.
 7. A process as claimed in claim 1 wherein said extrudateis formed of natural rubber, ethylene/propylene (EPM) copolymers,ethylene/propylene/diene (EPDM) copolymers, styrene/butadienecopolymers, chlorinated polyethylene, silicone rubber, thermoplasticvulcanizates (TPVs) or combinations thereof.
 8. A process as claimed inclaim 7 wherein the extrudate further comprises at least one materialselected from a material for blending or co-extrusion, a plasticizer, aviscosity modifier, a filler, a colorant, a curing agent, and anantioxidant.
 9. A process as claimed in claim 1 wherein said stufferprecursor is a compressed foam material which expands once inserted intothe hollow section.
 10. A process as claimed in claim 1 wherein saidstuffer precursor is a melted material which is injected into saidhollow section and which solidifies on cooling in order to form saidstuffer plug.
 11. A process as claimed in claim 1 wherein said stufferprecursor is a material which undergoes a chemical reaction onceinserted or injected into the hollow section, and forms a stuffer plugas a result of said chemical reaction.
 12. A process as claimed in claim1 wherein said stuffer precursor is a two part polyurethane.
 13. Aprocess as claimed in claim 1 wherein said stuffer precursor reacts toform a foam material.
 14. A process as claimed in claim 1 wherein saidstuffer plug fills an entire cross-sectional area of the hollow sectionof the extrudate, at or near the point of insertion of the dispenser.15. An extrudate produced from a process as claimed in any one of claims1 to
 13. 16. Use of an extrudate comprising a stuffer plug which hasbeen established within the extrudate using a process as claimed in anyone of claims 1 to
 13. 17. An apparatus for the on-line provision of astuffer plug within a hollow section of an extrudate, which apparatuscomprises a dispenser assembly having a needle-like section and astuffer plug precursor supply means for supplying stuffer plug precursormaterial to said dispenser assembly, wherein said needle-like section iscapable of being at least partially inserted, through the wall of theextrudate, into a hollow section within said extrudate so that saidstuffer plug precursor material can be fed through said needle-likesection of said dispenser into said hollow section in an operativeposition, and wherein said needle-like section is capable of beingsubstantially removed from the hollow section within said extrudate inan inoperative position.
 18. An apparatus as claimed in claim 17 whereinsaid dispenser comprises two or more needle-like sections.
 19. Anapparatus as claimed in claim 17 wherein said dispenser is part of adispenser assembly, which dispenser assembly comprises alignment railsfor positioning and holding an extrudate in an operative position, guiderails on which said dispenser is mounted and on which guide rails, saiddispenser can be moved, dispenser unit actuators for moving saiddispenser from a retracted position where it is not in contact with saidextrudate to, and from, an extended position wherein said needle-likesection pierces a wall of said extrudate and at least part of saidneedle-like section extends into a hollow section within said extrudate.20. An apparatus as claimed in claim 19 wherein said guide rails areessentially parallel to said alignment rails.
 21. An apparatus asclaimed in claim 19 additionally comprising a conveyor means for movinga length of extrudate into an operative position within said alignmentrails.
 22. An apparatus as claimed in claim 21 wherein said conveyormeans, said dispenser, and said dispenser unit actuators are controlledby processors so as to automate its use.
 23. An apparatus as claimed inclaim 19 comprising two or more dispenser units.